Fluidic control circuit for presses



April 21, 1970 D. J. MATTI-:SON

l FLUIDIC CONTROL CIRCUIT FOR PRESSES @01m n Nv 1A t X e e h s w 105.6 oNoNo m m/- l 3 moz@ u@ Nom N- om m@ Q z -IE Vl O NO N\/| o mOZm a om. 6w m, om l .n o p A m n 292Go.. o F owzmw ATTORNEYS April 21, 1970 D. .1.MATTEsoN 3,507,212

FLUIDIC CONTROL CIRCUIT FOR PRESSES Filed April lO, 1968 3 Sheets-Sheet2 Ful OTO- M ILM @mimi /e W uz l 5^@ PUSH To STOF( PULL To START BARBUN|V*.g OO\ 'Wrgig l I T M i l I L J 7e M FIG. 2

PRESS CRANKSHAFT POSITION (DEGREES) LSI o 9o |80 27o 36o DAV@ J M'Xlc FIG 3 LM 744m, ff: fw,

AT TOR N EYS April 21, 1970 D. .1Q MATTEsoN 3,507,212

FLUIDIG CONTROL CIRCUIT FOR PRESSES Filed April l0, 1968 5 Sheets-Sheet5 SEAL-IN 428 AND GATE C, FlG. 4

LATCH-m cl AND GATE Cgoz $50 TOR-STOP b 46 0 66 -H-\ XCI 9 NOR /45 64/C2 O2 l? START STGNAI. BRAKE CLUTCH INVENTOR.

DAVID J. MATTESON BY /l/feym, WMM @dy ATTORNEYS United States Patent O3,507,212 FLUIDIC CONTROL CIRCUIT FOR PRESSES David J. Matteson, DrexelHill, Pa., assignor to E. W. Bliss Company, Canton, Ohio Filed Apr. 10,1968, Ser. No. 720,249 Int. Cl. B30b 15/10, 15/12, 15/16 U.S. Cl. 100-5319 Claims ABSTRACT OF THE DISCLOSURE A fluidic control circuitespecially suitable for control of presses wherein a fluid NOR gateprovides a clutch signal in response to an input signal, andalternately, a 4brake signal with no input signal. The input to the NORgate is provided by components which cause the press to runcontinuously, or on a single stroke basis, with means to bring the pressto an emergency stop anywhere in the press stroke. Except for anemergency stop, provision is made so that the press stops only at thetop of its stroke. An initial but momentary start signal activates thecircuit and NOR gate clutch signal, the input to the NOR gate beingmaintained by an AND gate requiring continuous plural uid inputs so thatshould the uidic circuit be broken, or blocked in any way, the presswill fail safe and stop.

The present invention relates to a uidic control circuit, and inparticular, to such a circuit suitable for operation and control of apress.

It is known to provide an electrical circuit for presses and other typesof machinery, comprising tubes, relays and other components arranged tocause the press or other type of machinery to carry out a number offunctions.

Although the development of uidic components and circuits utilizingthese components is only recent, experience to-date has shown that thefluidic components and circuits offer many advantages over comparableelectrical components and circuits. For instance, it has been found thatthe uidic circuits are generally more reliable and dependable, andgenerally have a longer life not having components such as relays,subject to wear. When the circuits are preformed as an integratedassembly, they are tamper proof. In addition, it has been found that thefluidic circuits can be produced for less than the cost associated withcomparable electrical circuits.

In proceeding from an electrical circuit to the design of a uidiccircuit, the disadvantage arises that individual iiuidic components donot function or perform identically to the analogous electricalcomponents. This requires, in the design of a fiuidic circuit, the useof different concepts and logic.

It is an object of the present invention to provide a uidic controlcircuit particularly suitable for the operation of a press.

It is a further object of the invention to provide a uidic controlcircuit for a press which is inexpensive comprising a minimum andoptimum number of uidic components.

It is a further object of the present invention to provide a presscontrol circuit which fails safe in the event of a break or disruptionin the circuit.

In accordance with the invention, there is provided a fluidic presscontrol circuit which alternately activates a clutch mechanism and abrake mechanism, deactivating at the same time the mechanism notactivated, comprising a NOR gate including a clutch output connectionand a brake output connection. A fluid input connection actuates thepower fiuid ow in the NOR gate to the clutch output connection. An ANDgate comprises an output connection in ow communication with the NORgate input connection, -with means to interrupt either one or both ofthe inputs to the AND gate in the event any one of a number of stopconditions exists in the press. This in turn interrupts the NOR gateinput shifting the output thereof t0 the brake output connection. Atleast one of the input connections to the AND gate receives a signaldependent upon completion of the press stroke so that with the eX-istence of a signal at the other input connection, the press if stoppedis stopped only at the top of its stroke. This can be termed the normalstop input connection. An emergency stop means is provided in the ANDgate circuit designed to interrupt the signal to the other inputconnection causing the press to be stopped immediately. The AND gateconnection receiving this signal can be termed the emergency stop inputconnection.

Preferably, the normal stop input connection of the AND gate receives atleast two signals both dependent upon position of the press crankshaftin its stroke, both existing for a period or periods of the pressstroke. A rst means extends the first signal which can be termed atopstop signal for the period when the crankshaft is roughly between itspoint and its 270 point. A second means produces the second signalthroughout the press stroke except it may be interrupted when thecrankshaft is roughly at its point. This signal can be termed the repeatsignal.

In the absence of a repeat signal, the AND gate output is shut 01T asthe press passes the 270 point, the resultant absence of a NOR gateinput bringing the press to a stop at approximately 360. A PreferenceFlip-Flop (PFF) gate provides the repeat signal from its non-preferredoutput connection. The input to the PPF gate which holds the output atits non-preferred or repeat signal output connection is received from aseal-in AND gate. This AND gate contains a memory circuit whichremembers that the press was started, but in every cycle at the 180position, a momentary input which can lbe called an anti-repeat signalis received at the 'PFF gate input connection opposite the inputconnection receiving the seal-in AND gate output, and in the absence ofthe latter, the PFF gate output or repeat signal is turned off. Toterminate the sealin AND gate output, the AND gate is provided with avalve which interrupts the flow in its memory circuit.

The invention and advantages thereof will become apparent upon furtherconsideration of the following specification, with reference to theaccompanying drawings, in which:

FIGURE 1 is a ow circuit diagram illustrating a luidic control circuitin accordance with the invention;

FIGURE 2 is an electrical circuit diagram illustrating the manner inwhich the fluidic control circuit of FIG- URE 1 is energized;

FIGURE 3 is a graph illustrating control concepts of the invention andin particular the development of actuating signals in relation toposition of the press stroke; and

FIGURE 4 is a flow circuit diagram similar to FIG- URE 1 alsoillustrating the fluidic control circuit of the invention.

Referring to the drawings, and in particular FIGURE 1, the uidic circuitis generally designated with the numeral 12. Shop air is provided to thecircuit from a suitable source by means of inlet 14, passing through aplurality of conventional components to fluid input valves 16 and 18positioned in series in the input line 20, designed to transmit inputair to components 22 and 24, a PFF (Preference Flip-Flop) gate and anAND gate, re spectively.

The diamond arrowshaped symbol at the top of each gate indicates asupply fluid line attached to the gate. These lines are not shown in thedrawings to avoid confusion of such lines with the control lines.

Referring to the PFF gate 22, this component produces an output at 02with an input or signal at input connection C3. An input or signal at C1or C2 will produce an output at 01. The output will remain at theappropriate port (01 or 02) even when the control signal is removed.This device is known as a bistable memory. The C1 input accomplishes thesame function as the C2 input in this instance. The plus symbol in the02 corner of the PPF v gate indicates that this is the preferred outputconnection.

The AND gate as shown is an active AND gate requiring a continuous iiuidsupply at the top port, although it will be apparent to those skilled inthe art that a passive AND gate could be used (as item 24 or in theplace of other active AND gates in the circuit). The active and passiveAND gates can be used in various combinations, but not all, can bepassive. With no signals at C1 and C2, the output will be at 02. Anoutput at 01 can only occur if both C1 and C2 have positive signals.

The active AND gate is usually made from three NOR gates, the components26, 28 and 30 each being a NOR gate. The NOR gate has the uid powersupply at the top, as with the other components hereinbefore mentioned,and an output will always be present at either 01 or 02 depending uponthe signal condition at C1 (or other input connections of the NOR gate).With no signal at C1 or any other input connection, the output will beat 02. A positive signal at C1 or any input connection will switch theoutput from 02 to 01. When the signal at all input connections returnsto zero the output will switch back to 02.

The active AND gate is produced from the three NOR gates (26, 28 and 30)in the following Way. The 02 output of either or both of two of the NORgates 26 and 30 constitutes the input to the third NOR gate, item 28,either output causing an 01 output from the third NOR gate. To obtain an02 output from the third NOR gate (item 28), both of the first two NORgates 26 and 30 must have an input signal. In the absence of an input ateither of the NOR gates 26 and 30, there will be no 01 output at NORgate 28, or referring to AND gate item 24, in the absence of an input ateither C1 or C2, there will be no 01 output.

Other items of the circuit requiring preliminary discussion are theinterrupted Jet Sensor Limit Switches 32 and 34 (LS1 and LS2), andvalves such as SC1, item 36. Concerning the LS switches, referring toLS1 and gate 2NOR (item 38), a signal will appear at input connection C1of 2NOR to produce an 01 output as long as there is no obstruction inthe open gap between connections (1) and (2) for LS1. The obstructioncam 40y permits a signal at input C1 for the period of the stroke whenthe crankshaft is between 90 and 270 (notice FIGURE 3). Similarly, theobstruction cam 41 for Limit Switch LS2 (34) permits a signal at inputconnection C1 of gate INOR (item 43) except for a small period of thestroke when the press crankshaft is at about 180 (FIGURE 3).

The valves SC simply open and close lines of the circuit in aconventional way.

It is desired that the circuit cause the press to perform a number offunctions. For instance, it may be desired to have the press runcontinuously. Alternatively, it may be desired to have the press operateonly on a single stroke basis, or the operator may wish to simply jog orinch the press forward through a 360 crank rotation. In addition, it isnecessary that the operator be able to stop the press immediately in theevent of an emergency, but normally it is desired to have the press stopat the top of its stroke. In the event of any failure in the controlcircuit, it is necessary to have the press stop, or in other words, forthe circuit to fail safe.

All of these functions are provided in the following way. The press isprovided in a conventional manner with brake and clutch mechanismsdesigned to cause the press crankshaft to move through a stroke andalternatively to come to a stop. These mechanisms are usuallypneumatically actuated, and for the purpose of this disclosure, are

symbolically illustrated as a valve 42 for the clutch pneumaticmechanism and brake mechanism. A NOR gate 45 (identified as 9NOR)provides actuating ows to the valve 42, a 9NOR/01 ow actuating theclutch mechanism, a 9NOR/ 02 tlow actuating the brake mechanism. The9NOR output is either at 01 or 02 so that when the clutch is actuatedthe brake is off, and vice versa.

To start the press (by actuating the clutch), there must be a signal atthe C2 input of the 9NOR gate. This is provided from the output of01/1AND (item 24), and can be termed the press Start signal. An input atboth the C1 and C2 inputs of the IAND gate produces the 01 output.Valves 16 and 18 are normally open in branch conduit 20a of line 20 toprovide a C2 input at IPPF gate (item 22), which in turn has an outputat 01 providing a C1 input at IAND. As is characteristic of the 1PFFgate, termination of the C2 input does not disturb the 01 output, an 02output occurring only through an input at C3. When the pushbuttons at 16and 18 are both pushed, this provides a flow to the C2 input of IAND,which combined with the C1 input produces a 1AND/ 01 output and thedesired Start signal. The pushbuttons 16 and 18 are spring loaded sothat when they are released by the operator the C2/ 1AND input stops.This makes the Start signal or 1AND/01 output only momentary, or inexistence as long as the buttons 16 and 18 are depressed.

The 9NOR gate has a C1 input as Well as a C2 input. The C2 inputreceives the momentary start signal from (b1/AND, and to keep the clutchengaged, there is provided a Run signal at the C1 input. Providing theC1 input or Run signal is a Latch-in AND gate, described generally abovefor the purpose of describing an AND gate, comprising gates 6NOR, 7NOR,and SNOR and generally designated with the numeral 50. As mentionedabove an output from SNOR/ 02 required an input at both 6NOR and 7NOR,and the absence of an input at either of these gates results in ashifting ofthe output of gate SNOR from 02 to 01. To describe it anotherway, continuance of an input at C1/9NOR or continuance of the requiredRun signal to keep the clutch engaged requires an input at both 6NOR and7NOR. Itis noticed that the output connection of 02/8NOR (line 46) inaddition to having branch line 46a to C1/9NOR, has a branch line 46hrecycling a portion of the output to the input connection C2 of gate7NOR.

Initially, when 01/1AND was activated, it can be seen that the momentaryStart signal was transmitted to connection C1/7NOR as Well as C2/ 9NOR.At the same time, a signal was received at C3/ 6NOR in a manner to bedescribed, the two signals thereby activating the Latch-in AND gate.Recycle of a portion of the AND gate output of 02/8NOR effectivelyseals-in gate 7NOR and maintains an input at C1/9NOR. 'Ihe Run signal ofC1! 9NOR continues until something occurs to interrupt the inputs toeither GNOR or 7NOR.

The C3 input to gate 6NOR required for continuous running of the pressis obtained in the following way. Providing this signal is a Seal-in ANDgate generally designated with the numeral 48, made up of NOR gatesSNOR, 4NOR and SNOR (items 52, 54 and 56 respectively). The similarityof the configuration of these three gates to the Latchin AND gate or theactive AND (also called Nor Logic) circuit should be evident, theseal-in gate also including a conduit 58 receiving an output flow fromconnection 02/5NOR, and a branch conduit 58b in flow communication withthe input connection C2 of 4NOR, so that a portion of the AND gateoutput is recycled to the 4NOR gate to effectively seal-in the gate. Inoperation, the input connection C1 of gate 4NOR (54), along with the C1and C2 input connections of gates 7NOR and 9NOR respectively, receives alAND/ 01 output or Start signal initially in the start operation,producing an output at the 01 connection of 4NOR and no input at C2/SNOR. Similarly, in a manner to be described, there is established aninput at either of the C1 or C2 connections of gate 3NOR producing an 01output at this gate, and no input at the C1 connection of gate SNOR.With no input at either C1 or C2 of gate SNOR, an output is establishedat the output connection 02 of this gate and in the conduit 58, whichoutput is maintained by the portion of the output recycled to gate 4NOR,a branch 58a of the line 58 transmitting a portion of the flow toC3/6NOR.

During normal continuous operation of the press there will always be aninput signal at gate 3NOR (item 52). In the absence of such an input,the output of gate SNOR would switch from 02 to 01. To obtain a C2 inputat gate 3NOR, there is provided a gate 1NOR having input connection C1.A positive input ow produces an 01 output which is transmitted throughvalve SC1 (item 36) to the C2/3NOR input, as long as the SC1 valve isopen or switched to CONT., its continuous operation position. Shiftingthe valve 36 to SING, meaning single cycle, terminates the input at C2/3NOR, Providing the C1 input at 1NOR is Limit Switch LS2 (34). Exceptwhen cam surface 40 is positioned between connections (1) and (2) of theLimit Switch, the signal input at C1 will exist. As mentioned above, theconfiguration of the cam 41 is such that the signal input at C1/ INORwill be interrupted for only a very short period, and referring toFIGURE 3, it can be seen that the cam is so linked with the presscrankshaft that the signal interruption occurs when the press crankshaftis approximately at 180 To obtain a signal at the other input connectionC1 of gate 3NOR, the connection is placed in flow communication 'withthe output connection 01 of gate ZNOR (38) the latter receiving a signalfrom Limit Switch LS1. This Limit Switch is cammed, referring to FIGURE3, to produce a signal at C1`/ 2NOR, and a 2NOR/ 01 output, when thepress crankshaft is between 90 and 270, including the period when thereis no input at the C2 connection of gate SNOR.

Accordingly, there will always be, during normal continuous operation ofthe press an input signal at either C1 or C2 of 3NOR. This coupled withthe C2r/4NOR Seal-in input maintains the SNOR output at 02 and the inputto C3/ 6NOR, or operation of the press.

The portion of the circuit including the gates 3NOR, 4NOR and SNOR,producing the C3 signal continuously at gate 6NOR, is what may beconsidered the memory portion of the circuit that logically remembersthat the pushbuttons 16 and 18 'were depressed and that the mode ofoperation of the press is continuous. Even though the initial startsignal to C2/ 9NOR was only momentary and terminated with release of thepushbuttons 16 and 18, the continuous input at C3/ 6NOR maintains theinput at C2/ 9NOR causing the latter gate to maintain the 01 clutchoutput flow.

Should there be a power loss, the memory would self destruct and thepress would automatically stop.

It should be noted that the 01 output of gate ZNOR (38) also produces asignal or input flow at the C1 input connection of gate 6NOR. Forpurposes of this application, this signal can be referred to as theTop-Stop signal, and as will be shown, the signal is used to bring thepress to a normal stop at the top of its stroke, and is maintained forthe necessary period to accomplish this function.

Providing an input at the C2 connection of gate 6NOR is gate ZPFF (item62) from connection 01. This signal can be called a Repeat signal forreasons to be described. Actuation of the gate 2PFF to an 01 output isaccomplished by an input at C2/4NOR obtained as a portion of the SNORoutput, the input to gate ZPFF being through branch line 58C. As ischaracteristic of a PFF gate, the output will remain at 01 untilswitched to 02 by an input at connection C2. The latter connection is inow communication with the 02 output of gate INOR (43), and the signal toC2/ ZPFF for reasons to be shown can be called the Anti-repeat signal.

At this point, two other items of importance should be mentioned,Emergency Stop Button (EMG) 64 and Top-Stop. button 66, the former beingpart of the Latch-in AND gate circuit 50, the latter part of what hasbeen termed the Seal-in AND gate 48 comprising NOR gates 3NOR, 4NOR andSNOR.

The meaning of the terms Emergency Stop and Top- Stop should beself-evident, namely that the EMG button 64 brings the press to a stopanywhere in its cycle in the event of an emergency situation, theTop-Stop button bringing the press to a stop at the end or top of astroke.

The emergency stop procedure is very simple, affected by pushingEmergency-Stop button 64. This interrupts the input to 7N OR (therelease of start buttons 16 and y18 terminated the C1 input to thisgate) producing Ian 02 output, and accordingly a C2 input at SNOR.Immediately, the output at `8NOR switches from 02 to 01 breaking theinput at C1/9NOR, causing the output'at 9NOR to switch from 01 to 02.This deactivates the clutch mechanism and activates the brake mechanismat the same time, and brings the press immediately to a stop anywhere inthe stroke cycle.

As the name implies, the emergency stop should only be used whenpersonal injury or mechanical failure may result. Ordinarily it isdesired that the press stop at the top of its cycle, since should itstop at the bottom it becomes very difficult to clear the press andcontinue operation.

A normal or Top stop is achieved by pushing Top- Stop button 66interrupting the seal-in portion of the circuit 4S, namely terminatingthe C2 input to gate 4NOR. This shifts the output at SNOR from 02 to 01,thereby terminating the C3 -inp-ut to 6NOR. The C2 input at 6NOR may bemaintained, at least for -a period of the stroke, since in the absenceof a C2 input at the 2PFF gate, the output will remain at 01, eventhough the C1 input was interrupted by pushing button 66.

However, very quickly, at the 180 position of the press crankshaft,FIGUR-E 3, there lis a C2 input at ZPFF (from 02/1NOR in that C'I/INORwa-s rmomentarily interrupted) shifting the output to 2PFF/02. Now, inthe absence of a C1 input (SNOR being turned off) the output will remainat 02 termin-ating the C2 input to 6NOR.

Still the press will continue to run by virtue of the C1/ 6NOR inputsignal from 'LSL but as shown on FIG- URE 3, this is interrupted whenthepress reaches about 270 by virtue of cam 40, bringing the press to aStop at about 360 or the top of its stroke.

If the operator had pushed the Top-Stop button 66 when the presscrankshaft was near the end of a stroke or beginning a new stroke,between the positions 270 and FIGURE 3, there would be no C1 input at6NOR (LS1/2NOR lbeing turned olf) or C3 input. The press is carriedthrough the next stroke to a Top-Stop position by a 2PFF/01 output andinput at C2/6NOR or the Repeat signal, until this is turned-01T by theAntirepeat signal or 1NOR/02 output at about 180. The C1/6NOR Top-Stopinput then stops the press at the top position in the usual manner.

The significance of the terms Repeat signal (C2/ 6NOR), Anti-repeatsignal (C2/2PFF) and Top.. Stop signal (C1/6NOR) should be evident. Onevery cycle at about the switch L52 switches 1NOR to an 02 outputmomentarily, tending to trigger the `ZPFF gate to an 02 output. This isthe Anti-repeat signal and in the absence of an output from the memoryportion of the circuit (gates 3NOR, 4NOR and SNOR) which remembers thatthe start buttons were pressed, the press will be brought to a stop lbythe Top-Stop signal at about 300. However, with an output from thememory gate, i.e. from OZ/SNOR, should the operator have delayed pushingthe Top-Stop button past the 180 point, the

'C1 input at 2PFF will force the output to remain at 01.

Accordingly, even though the C3 and C1/'6NOR inputs are then terminatedthe press will repeat its stroke to come to a stop at the end of thenext stroke.

The logic of the circuit can perhaps be better visualized from FIGURE 4which shows gates 48 and 50 using the active AND gate configuration. TheC2 input connection of gate 50 can be termed the emergency stop inputconnection and the C1 input connection can be termed the normal stopinput connection. In the absence of an input at either connection the9NOR gate switches from a clutch output to a brake output. Connected tothe normal stop input connection C1 of gate 50 are 3 input sources, onefor continuous running which remembers that the start pushbuttons werepressed |(AND gate 48), the other two being designed to maintain aninput signal so that the press stops at a predetermined desired point inits stroke.

For single stroke operation, valves SCI and SC2 (36 and 65) are moved tothe open position. This in effect removes BNOR, SNOR, 4NOR and ZPFF fromthe operating circuit. (See FIGURE 1.)

The press is started by depressing the run/jog pushbuttons 16 and 18Vwhich along with 01/1PFF activates 01/1AND. The press will begin tostroke as soon as 01/1AND trips 01/9NOR. if the operator removes hishands from the run/jog push-buttons before the press reaches 90, thepress will stop. After the press reaches 90, LS1 trips ZNOR and an inputsignal will appear at C1/6NOR. With inputs on 6NOR and 7NOR, OZ/SNORwill seal in C2/7NOR and the operator can remove his'hands from thepushbuttons. When the press reaches about 270, the signal from 01/2NOR4will cease causing GNOR, 7NOR, SNOR and 9NOR to turn off. The presswill then stop.

If the operator had held the push-buttons down, maintaining a signal atinput C2/9NOR, the press would still :have stopped on top positionbecause of the action of the anti-repeat signal. During the stroke, atabout the 180 position, -LS2 causes a signal to result from 02/1NOR toC3/i1PFF. This will turn the memory oit killing 01/ IIAND, and thus theinput at BNOR. The sequence for single stroke stopping would then be thesame. Should the press coast beyond top position and on to 90, the presswill not restart unless the operator react-ivates the run/ jog buttons.

An important safety aspect of the circuit should be mentioned. Aspreviously indicated the PPF gates 22 and 62 have an initial orpreferred output at the 02 output connections prior to the press beingstarted or prior to an input signal. Thus, even though air is suppliedto the diamonds of these gates from valve 80, the circuit will notassume an operator command not in fact directed by the operator. Shouldthe ini-tial output from ZPFF, for instance, be at connection 01, thepress would not stroke, but it would compromise the inherent safetyprovided -by the design. A Preference Flip-Flop gate can be replaced bytwo NOR gates in a manner well known to those skilled in the art.

Providing the C1 input to gate lPFF is valve 82 (R11) which ismechanically connected to valve 84 (1R12) in line 46 (the 02 output lineof SNOR) so that when R11 is open R12 is closed and vice versa. Aselector switch moves the valves between what can he termined Run andJog positions. In the normal Run position R11 is closed (no iiow toC1/2PFF) and R12 is open, but if the operator desires to inch or jog thepress forward, distinguished from single stroke or continuous operation,valve R11 is moved to its open position and R12 is closed. This providesa continuous C1 input to 1PFF and interrupts the output of SNOR, thelatter step effectively remov-ing the seal in portions (3NOR-8NORinclusive) from the circuit. Pressing the Run/Jog buttons 16 and 18activates 1 AND to provide a C2/ 9NOR input, which is immediately-interrupted on release of the buttons, and the press stops in theabsence of the signal from SNOR.

The Bar-Run switch 70 is normally in the run position to transmit shopair to the circuit via line 20, but in the bar position it turns off thepress motor and engages the clutch to permit the operator to bar-movethe press to desired positions.

In place of gate 9NOR, a PPF gate could be used with C1 and C2 inputconnections producing 01 clutch and 02 brake outputs respectively. TheSNOR/ 02 output would be connected at the C1 input to produce the clutchsignal, and the SNOR/ 01 output would be connected at the C2 input toproduce the brake signal. The disadvantage is that should the C2 inputbe blocked there would be no way to stop the press. Accordingly, the useof a NOR gate is preferred.

FIGURE 2 simply illustrates a suitable electrical circuit. A three-phaseinput is supplied to the press motor 74, transformer 76 supplying atwo-phase current to solenoid 78, the current actuating solenoid valve80 in the air supply line.

Should any of the tubes connected to this iiuidic system be broken, thepress would fail safe. If dirt blocks LS1 or LSZ, the press would stop.

It will be apparent to those skilled in the art that an aspect of theinvention resides in a fluidic press control circuit in which the failsafe and emergency stop functions are generated by a lost signalconguration.

What is claimed is:

1. A uidic press control circuit which alternately activates a clutchmechanism and a brake mechanism comprising:

a uid gate including clutch and brake output connections and at leastone input connection, an input producing an output iiow at the clutchconnection;

an AND gate including an output connection in ow communication with thetiuid gate input connection, an input `at both of the input connectionsof the AND gate producing an output at the output connection thereof;

first recycle means connected to said AND gate output connection in owcommunication with one of the AND gate input connections; to recycle aportion of the AND gate output to the AND gate input connection; v

means producing a signal at the other of said AND gate inputconnections;

stop means to interrupt the input to at least one of said AND gate inputconnections.

2. A circuit according to claim 1 wherein the first recycle meansconnected between the AND gate output connection and the AND gate inputconnection includes an emergency stop valve to interrupt the ow therein.

3. A circuit according to claim 2 further including means producing thesignal to the other of said AND gate input connections responsive to thepress crankshaft position, whereby the press can be stopped at apredetermined point in its stroke.

4. A circuit according to claim 1 wherein said AND gate includes iirstand second input connections and second input connection being in iiowcommunication with the output thereof, further including a second ANDgate of the same configuration as said first mentioned AND gateincluding an output in flow communication with the iirst inputconnection of the first mentioned AND gate also including second recyclemeans in ow communication with an input connection of the second ANDgate to recycle a portion of the second AND gate output to the secondAND gate input connection:

emergency stop means to interrupt the recycle ow in said iirst recyclemeans;

means to interrupt the recycle ow in said second recycle means;

means to maintain a signal at the first mentioned AND gate first inputconnection until the press crankshaft reaches a predetermined positionin its stroke.

5. A circuit according to claim 1 wherein said uid gate is a NOR gate.

6. A uidic press control circuit which alternately actition of thelatch-in AND gate when the output of vates a clutch mechanism and abrake mechanism comthe seal-in AND gate is interrupted until the pressprising: crankshaft reached a predetermined point in its a 9NOR gateincluding an 01 clutch output connection, stroke.

an 02 brake output connection, an input producing 5 9.A A controlcircuit according to claim 8 wherein said an 01 output; last-named meanscomprises a first signal means and a a first AND gate including 6NOR,7NOR and SNOR second signal means both in flow communication with thegates, means to transmit the `SNOR/ 02 output to the first inputconnection of the latch-in AND gate;

one of said signal means constituting a top-stop signal meansmaintaining a iiow to said latch-in AND gate first input connection upto a predetermined point close to but prior to the press stroke topposition the interruption of which causes the press to stop at the topof its stroke;

the other signal means constituting a repeat signal means the presenceof which causes the press to continue operation despite interruption ofthe top-stop signal.

10. A control circuit according to claim 9 wherein said GNOR gate as aninput thereat; 2() first and second recycle means to recycle portions ofthe 8NOR/02 and 5NOR/02 outputs respectively as inputs to 7NOR and 4NORrespectively; emergency stop means to interrupt the recycle iiow in saidfirst recycle means; top-stop means to interrupt repeat signal meanscomprises a PPF gate including C1 and C2 input connections and 01 and 02output connections, a C1 input producing an 01 output, a C2 inputshifting the output to the 02 output connection and vice versa, the PFFgate 01 output being in flow communication with the latch-in AND gatefirst input connection;

the recycle fiow in said second recycle means; means to maintain aninput to said 6NOR gate even after interrupting the iiow in said secondrecycle means until the press crankshaft is at a predetermined means toproduce an anti-repeat signal at a predetermined point in the presstroke at the C2/ PFF input connection to cause the output to shift fromthe 01 to the 02 .output connection;

position in its stroke.

7. A circuit according to claim -6 wherein said lastmentioned meanscomprises:

a first sensing device to produce a 6NOR gate input when the presscrankshaft is between about 90 and about 270; 35

a ZPFF gate including 01 and 02 outputs responsive to C1 and C2 inputsrespectively; means to transmit the PFF gate 01 output to said 6NOR gateas an input thereat;

means to transmit a portion of the SNOR/OZ output to the C1 inputconnection and the 2PFF gate;

a second sensing device to transmit a signal when the press crankshaftis at about 180 to the C2 input connection of the 2PFF gate;

the C1/ PFF input connection being in fluid communication with theseal-in AND gate output connection whereby the shift from CZ/PFF 01 to02 occurs only in the absence of the seal-in AND gate output.

11. A control circuit according to claim 10 wherein both said signalmeans include jet-sensor limit switches with cam means connected to thepress stroke designed to produce the signals thereof at predeterminedpoints.

12. A control circuit according to claim 10 wherein the seal-in AND gatefirst input connection receives a signal at all times during pressoperation from one of said signal means in continuous mode operation.

13. A iiuidic press circuit according to claim 12 wherein said repeatsignal means comprises a jet sensor limit switch;

the output of the `2PFF gate transferring to the 02 -munication with theNOR gate input connections, an input at both the input connections ofthe AND gate producing an output at the output connection thereof;

first recycle means connected to said AND gate output connection in owcommunication with said second input connection of said AND gate, saidrecycle means including emergency stop means to interrupt the flowtherein;

a second NOR gate including an input connection and connection in theabsence of an 02 output from the 45 01 and 02 output connections, aninput producing an SNOR gate. 01 output;

8. A iluidic press control circuit which alternately meansCOInnlnniCaiing the let SenSOl limit SWiCh With activates a clutchmechanism and a brake mechanism the NOR gaie inPnt, the 02 On'fPnt beingin fiOW Colncgmprising; munication with the CZ/PFF input connection, the

a NOR gate including clutch and brake output con- 91 Output being in HOWCommunication With the firSt nections and an input connection, an inputproinput connnniinn 0f the Seal-in AND gate;

ducng an output ow at the clutch connection; cam surface means connectedto the press stroke intera latch-in AND gate including first and secondinput fnnnng the C1 inPllt 0f in@ NOR gaie Causing a CZ/PFF connectionsand an output connection in iiow com- Input;

14. A control circuit according to claim 13 wherein said 01/NOR outputis blocked for single stroke operation of the press;

said top-signal means producing an input at the latchin AND gate firstinput connection and at the seal-in AND gate rst input connection forabout the portion of the stroke from 90 to about 270;

a seal-in AND gate including first and second input an anti-repeatsignal from the second signal means to connections and an outputconnection in fiow com- CZ/PFF maintaining an input at the first inputconmunication with the first input connection of said nection of thelatch-in AND gate to cause the stroke latch-in AND gate, an input atboth the input conto continue to its top position. nections of theseal-in AND gate producing an 15. A control circuit according to claim12 wherein said output at the output connection thereof; repeat signalmeans comprises:

second recycle means connected to said seal-in AND gate outputconnection in ow communication with the first input connection thereofincluding top-stop means to interrupt said input;

means to maintain a signal at the first input connecsive to a positiveinput and an 02 output connection responsive to no input; n

rst means transmitting said 01 output to the seal-in AND gate firstinput connection;

second means transmitting the 02 output to C2 input connection of thePFF gate;

means to interrupt the flow in said iirst means or single strokeoperation.

16. A liuidic press control circuit which alternately activates a clutchmechanism and a brake mechanism comprising:

a NOR gate including clutch and brake output connections and an inputconnection, an input producing an output iiow at the clutch connection;

iirst AND gate means including first and second input connections and anoutput responsive to inputs at both said input connections;

means transmitting the AND gate means output to the NOR gate inputconnection;

emergency stop means to interrupt the input to the second of said ANDgate input connections, said input being a portion of the AND gate meansoutput ow;

second AND gate means including first and second input connections andan output connection in flow l communication with the other of saidiirst AND gate means input connections, an input at both the inputconnections of said second AND gate means producing an output at saidoutput connection;

start signal means providing an input flow to the second inputconnection of said second AND gate;

said start signal means comprising a third AND gate including iirst andsecond input connections, an output responsive to an input at both theinput connections thereof;

spring-loaded valve means supplying a flow to the second of said thirdAND gate input connections whereby the output of said third AND gate ismaintained as long as the valve means is held open;

means to recycle a portion of the second AND gate output to the secondinput connection thereof to maintain an input at said connection evenwhen said valve means is closed terminating said start-signal.

17. A circuit according to claim 16 including means to interrupt theportion of the second AND gate output flow recycled to the second inputconnection thereof.

1S. A iiuidic press control circiut comprising:

tirst and second switch means including tirst and second cam means tointerrupt the output How therefrom;

rst and second NOR gates including input connections in flowcommunication with said switch means outputs respectively, furtherincluding 01 and 02 output connections, in input producing an 01 output;

a latch-in AND gate including first and second input connections, apositive input at both said input connections producing an output;

means communicating the iirst NOR gate 01 connection with said latch-inAND gate iirst input connection, said tirst cam means interrupting theow at a predetermined first point in the press cycle;

a seal-in AND gate also including rst and second input i connections, apositive input at both said input connections producing an output;

said first NOR gate 01 connection also being in communication with saidseal-in AND gate lirst input connection;

means communicating the second NOR gate 01 connections with said seal-inAND gate first input connection;

anti-repeat signal means communicating the second NOR gate 02 connection`with said latch-in AND gate first input connection including a PFF gateand an 01 output therefrom in communication with s'aid rst inputconnection;

means communicating the seal-in AND gate output with said PFF gatewhereby the AND gate output produces at latch-in AND gate input;

the 02 signal from said second NOR gate interrupting the input to saidlatch-in AND gate when the sealin AND gate output is terminated;

said second cam means resulting in an 02 signal from said second NORgate at a point in the press cycle earlier than said first-mentionedpoint.

19. A uidic press control circuit comprising:

a fluid gate including 01 and 02 output connections and at least oneinput connection to producean 01 output;

start signal means to provide at least a momentary iiow to said inputconnection;

memory circuit means responsive to said start signal means ilow toproduce a continuous iiow to said input connection;

said start signal means comprising and AND gate including C1 and C2input connections and an 01 output connection producing said liow;

a second gate including an 01 output connection in dow communicationwithsaid AND gate C1 input connectio-n;

first, second and third fluid input lines, the second and third inputlines being connected to said second gate to produce said 01 output, thefirst line being connected to the AND gate C2 input connection;

iirst, second and third valve means in said input lines;

a fourth valve means in said memory circuit means to interrupt saidcontinuous ow;

a iirst selector switch to alternatively open and close said first andsecond valve means;

a second selector switch to alternatively open and close said third andfourth Valve means whereby when said memory circuit means continuous owis interrupted, the press can be inched forward by closing said firstValve means.

References Cited UNITED STATES PATENTS BILLY I. WILHITE, PrimaryExaminer U.S. Cl. XR.

